Founders sometimes ask me if some piece of conventional wisdom they've heard or the advice that I'm giving is "necessary" or "mandatory".
I always try to explain that almost all of the tactics and advice I'm sharing can only increase the probabilities of success. It can't guarantee it. There's also always a chance you can succeed without following any given piece of "best practice" advice.
That being said, if you start bending or breaking too many of these guidelines you really start to diminish your chances of success.
Funny enough, many of the lessons I share day-to-day were not learned from a book or from someone else giving me the advice - I had to learn them the hard way by ignoring the advice in the first place (thinking I had a better way) and finding out I was wrong.